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Finding the Fourth Proportional to 254.58, 381.92 and 81.21

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Solution

The fourth proportional to 254.58, 381.92 and 81.21 is: 121.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    254.58 : 381.92 = 81.21 : x
  2. Step 2: Convert to fraction form
    254.58/381.92 = 81.21/x
  3. Step 3: Cross multiply
    254.58x = 381.92 × 81.21
  4. Step 4: Simplify right side
    254.58x = 31,016.75
  5. Step 5: Solve for x
    x = 31,016.75/254.58
  6. Step 6: Final answer
    x = 121.84

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.